1TB NVME drives aren't very expensive on the order of $80-$100 US. This is already big enough for your entire OS even with several very large games installed. The natural split if you have multiple drives would be between OS and backups/multimedia.
I see this immediately being used for pirated software and games. It could also be used to implement a cross platform app store like interface to install legitimate software. It could even be integrated with the same store interface as one uses to install traditional packages and flatpaks for a true one stop shop.